I found the corsair link software to be a cpu hog, at least with a Celeron, and only when I was looking at it...
I've got it turned off now on those machines, you can always run it manually as a 1 off to check consumption if you're tuning, then disable later.

Been messing around with a faulty board, and i had that Afterburner cpu lagging issue pop up when a particular GPU was having connection issues. Swapped gpu's and so far an hour in the problem hasn't returned.

Takes so much time to isolate each issue

So it could be a loose m.2 or usb cable if that afterburner issue is recurring for you

Strange but MSI afterburner is now hovering abut 17% CPU load, whereas with the lower clocking Celeron it was closer to 50%!!

Click to expand...

On my 8 card rig, Afterburner is chewing between 17% and 26% cpu on a G3930. Hadn't even thought to check before seeing this thread (but I haven't seen any rate fluctations like you, so hadn't need to look around).